Heavy eye syndrome versus sagging eye syndrome in high myopia

BackgroundHeavy eye syndrome (HES) presents with esotropia and limited abduction due to superotemporal globe shift relative to the extraocular muscles. Sagging eye syndrome (SES) was originally described in nonmyopic patients exhibiting distance esotropia and cyclovertical strabismus with limited supraduction due to lateral rectus muscle inferodisplacement caused by degeneration of the lateral rectus–superior rectus (LR-SR) band. We hypothesized that SES might also cause strabismus in high myopia.MethodsEleven strabismic subjects with high myopia underwent ophthalmological examination and orbital magnetic resonance imaging (MRI) to assess quantitative orbital anatomy.ResultsOf 11 subjects, 5 had HES; 6, SES. Mean axial length in subjects with HES was 32 ± 5 mm; in subjects with SES, 32 ± 6 mm. Average distance esotropia in subjects with HES was 61Δ ± 39Δ; hypotropia was 26Δ ± 21Δ. Average distance esotropia in subjects with SES was 23Δ ± 57Δ; hypertropia was 2Δ ± 2Δ. All 5 subjects with HES had superotemporal globe prolapse; the LR-SR band was thinned in 6 orbits and ruptured in 2. The mean angle between the lateral rectus and superior rectus muscles in HES was 121° ± 7°. In SES the LR-SR band was thinned in 7 orbits and ruptured in 5, with superotemporal soft tissue prolapse. The mean angle between the lateral rectus and superior rectus muscles was 104° ± 11°, significantly less than in HES (P < 0.001).ConclusionsSES occurs in highly myopic patients who also exhibit less relative globe dislocation than in HES. Unlike HES, SES exhibits superotemporal soft tissue prolapse that may limit superotemporal globe shift. The distinction is important because surgery for HES uniquely requires creation of a surgical connection between the superior rectus and lateral rectus muscles, whereas SES may be treated with conventional surgery. SES can cause strabismus in high axial myopia. Orbital MRI is useful in differentiating SES from HES.